According to the classification presented in the illustrated book "A LOCOMOTIVE G-12", by José Agenor S. Ferreira, this is phase II of these locomotives in Brazil.

Manufactured in 1957, these locomotives have the biggest difference in relation to the other G-12s, the 3-axle truck, with the center wheel, with a smaller diameter, only serving to distribute the weight of the locomotive, not being motorized. Therefore, they are classified as G-12 A-1-A, that is, 3 axles with a free central axis.

20 locomotives were acquired, which arrived in Brazil in 1957, even when Viação Férrea Rio Grande do Sul (FVRGS) had not been incorporated into RFFSA. Later they passed to RFFSA, as per our model, and even later they were re-allocated to other RFFSA regions, with the bogies being changed from A-1-A to B bogies.

The FRATESCHI model also has the A-1-A trick as a distinguishing feature, which was built according to our latest quality standard, with very high fidelity to the details of the prototype, and extremely smooth operation, with the steering wheels centered at a level of precision. very rigorous, and the new lighting using reversible LEDs, with constant intensity.